جستجوی مقالات مرتبط با کلیدواژه "langmuir" در نشریات گروه "پزشکی"

Chromium (Cr), as a metallic pollutant, enters to the body through drinking water. Due to the toxic and dangerous characteristic of hexavalent chromium, its removal is necessary. In this research, titanium dioxide nanoparticles were used as an adsorbents to remove Cr from water. The characteristic of TiO2 nanoparticles were determined using XRD and FTIR analyses. Batch adsorption experiments were performed using synthetic aqueous solutions containing chromium. The optimal conditions of adsorption were investigated at various pHs, initial concentration of metal ion, contact time and the adsorbent dosage on Cr adsorption capacity. Also, the study was carried out ethically and there was no bias and confinement on the part of the researcher during the research process. The results showed that the removal percentage at pH=3 (88.50%) was significantly more than the other studied pHs. The lowest removal percentage was observed at pH = 9 (38.03%). at the highest Cr adsorption was noticed in concentration of 0.5 g/L (61.52%), which was statistically significant as compared to other concentrations Accordingly, the lowest adsorption was observed at 5 g / L concentration (6.75%). Adsorption performance was not significantly different at different times, and the amount of adsorption was almost constant after 30 minutes. Cr adsorption by TiO2 nanoparticles increased with increase in adsorbent dose and the maximum amount of adsorption occurred at 4 g/L (68.31%) which again was significantly higher than other studied dosages. The lowest removal percentage was observed at 1 g/L (18.57%). The sorption isotherm studies showed that adsorption of chromium by titanium dioxide was fitted well to Freundlich isotherm model (R2 = 0.78). Titanium dioxide demonstrate high efficiency in adsorbing chromium from wastewater and thus can be a promising sorbent for the treatment of industrial wastewaters

Dye effluents of some industries include many toxic, carcinogenic, and mutagenic compounds; therefore, colored contaminants of such industries should be carefully treated using an appropriate method before discharging wastewater to the environment. This study aimed to evaluate the performance of Multi-Walled Carbon Nanotubes (MWCNTS) as an effective adsorbent in removing Acid Black 1 (AB1) from colored wastewater.
This laboratory study was conducted in the batch system and MWCNTS was used as an adsorbent to remove AB1 dye. The effect of various factors influencing dye removal, such as adsorbent dose, initial dye concentration, contact time, and pH investigated in this study.
The results showed that pH=3 was the best pH for dye removal and the equilibrium time for AB1 dye adsorption on MWCNTS was 60 minutes. As dye concentration increased, dye removal rate decreased. Besides, increasing the amount of adsorbent increased the dye removal efficiency and at the adsorbent dose of 600 mg/L, dye removal efficiency was 98.86% and 94.62% for 30 and 50 mg/L dye concentrations, respectively. Also, AB1 dye removal followed Langmuir isotherm and Pseudo-second-order kinetic models.
The results of adsorption studies showed that by increasing the contact time and the adsorbent dose and reducing the pH, dye removal efficiency was also increased. In addition, MWCNTS could be used as an efficient adsorbent for decolorization of azo dyes from wastewater.

Furfural is one of the toxic chemical compounds used in many industries such as petrochemical, food, paper products, pharmaceutical, etc., due to having some characteristics. Therefore, furfural could be found at different concentrations in the effluent from these industries and can enter the environment. Hence, the aim of this study was the assessment the efficiency of a low cost bentonite modified with cationic surfactant in the removal of furfural from aqueous solution. In this experimental study, bentonite was purchased from one of the Mines of Zanjan Province, Iran and then the efficiency of bentonite modified with the cationic surfactant CTAB (CTAB-Bent) was assessed in the adsorption of furfural from aqueous solution. Activated carbon (AC) was also purchased as commercial grade. Under optimum conditions, the removal efficiency of AC and CTAB-Bent was about 52 and 66%, respectively. For both adsorbents used in this study, the increase of contact time and sorbent dosage resulted in increasing the removal efficiency, but the removal efficiency was decreased with the increase of furfural initial concentrations. Regarding pH, the removal efficiency was the highest in relative acidic and neutral environment, (60 and 69% for AC and CTAB-Bent respectively). The kinetics studies revealed that the highest correlation coefficients were obtained for the pseudo-second order rate kinetic model. Adsorption data from both adsorbents was also fitted with Langmuir isotherm. It was found that modified bentonite with CTAB as a natural adsorbent could have better efficiencies compared with activated carbon in the furfural removal, although more contact times is needed.

Dye effluents of some industries contain many toxic, carcinogenic, and mutagenic compounds therefore, wastewater colored contaminants of such industries should be meticulously refined using an appropriate method before discharging waste-water to the environment. Therefore, this study aimed to evaluate the effectiveness of Multi-Walled Carbon Nanotubes (MWCNTS) in dye removal of Acid Black 1 (AB1) from colored wastewater. This laboratory study was conducted in the batch system and MWCNTS were used as absorbents to remove AB1 dye. In fact, this study investigated the effect of various factors influencing dye removal, such as adsorbent dose, initial dye concentration, contact time, and pH. The study results showed that pH=3 is regarded the best pH for the dye removal. The equilibrium time for AB1 dye absorption on MWCNTS was 60 minutes. As dye concentration increased, dye removal rate decreased. Besides, increasing the amount of adsorbent increased the dye removal efficiency and at the absorbent dose of 600 mg/L, dye removal efficiency was reported 98.86% and 94.62% for 30 and 50 mg/L dye concentrations respectively. AB1 dye removal followed Langmuir isotherm and Pseudo-second-order kinetic models. The results of absorption studies revealed that increasing the contact time and the absorbent dose as well as reducing the pH lead to an increase in dye removal efficiency. Overall, the study findings demonstrated that MWCNTS could be used as an efficient absorbent in regard with decolorization of azo dyes from wastewater.